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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 7 |
| 3 | 19 |
| 4 | 187 |
| 5 | 437 |
| 6 | 1979 |
| 7 | 4387 |
| 8 | 76627 |
| 9 | 165409 |
| 10 | 707825 |
| 11 | 1503829 |
| 12 | 12706671 |
| 13 | 26713417 |
| 14 | 111868243 |
| 15 | 233431331 |
| 16 | 7770342787 |
| 17 | 16124087129 |
| 18 | 66765132341 |
| 19 | 137948422657 |
| 20 | 1138049013461 |
| 21 | 2343380261227 |
| 22 | 9636533415373 |
| 23 | 19787656251221 |
[0,1,7,19,187,437,1979,4387,76627,165409,707825, 1503829,12706671,26713417,111868243,233431331, 7770342787,16124087129,66765132341,137948422657, 1138049013461,2343380261227,9636533415373, 19787656251221] |